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CS 5631 Study Questions and Homework

Distributed Operating Systems

Chapters 15-15.5, 16-16.4, 16.6, 17.1-17.3

Homework 8

Homework (5 points) due Tuesday, April 27, 2004.

For Homework 8, turn in your answers for the following study questions: 1, 4, and 9.

Homework 9

Homework (6 points) due Tuesday, May 4, 2004.

For Homework 9, turn in your answers for the following study questions: 6, 7, 12, and 14.

Study questions

  1. What is a distributed operating system? Give the specific meaning.

  2. List some advantages of a distributed operating system.

  3. What does transparency mean in the following contexts?
    1. computation in a distributed system
    2. file storage in a distributed system

  4. You have narrowed down your choice for network topology to either a fully connected topology or a star topology. Discuss how your final choice will affect the following.
    1. installation cost
    2. communication speed
    3. robustness (availability)

  5. Contention is described in the text as an important communications issue. In what context is this true? What does it mean in that context?

  6. What kind of entities are peers in the following protocols?
    1. TCP (ISO transport layer)
    2. IP (ISO network layer)
    3. Ethernet (ISO data link layer)

  7. There are two ways of specifying a machine on the internet: names such as ub.d.umn.edu, and addresses such as 131.212.161.1. Why is is desirable to have both ways of specifying a machine?

  8. While transmitting a packet, the TCP layer sends 100 bytes to the IP layer. What can you say about the amount of data sent by the IP layer to the next lower layer. Why is there a difference?

  9. What does naming mean in the context of distributed file systems? How is it related to transparency?

  10. What is the difference between stateful and stateless file servers? What is the most important problem with each approach? What is the best solution to both problems?

  11. Sketch what is involved in converting the UNIX file system software to a distributed file system. You should deal with both file naming and file access.

  12. What are Vice, Virtue, and Venus?

  13. After a file has been opened in the Andrew File System, how are file blocks accessed?

  14. To implement timestamping across a network, every communicating process maintains a local clock. How are the clocks synchronized?

  15. In the Two-Phase Commit Protocol, what must happen before the transaction coordinator send a COMMIT message to the participating sites?

  16. In the Two-Phase Commit Protocol, what is the purpose of logging?

For the final, you should also review the following web pages:

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